Flame retardant polycarbonate composition

ABSTRACT

A flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of unsubstituted or halogenated oxocarbon acids, or mixtures of these.

This is a continuation, of application Ser. No. 642,944 filed Dec. 22,1975 now U.S. Pat.4,069,201 which in turn is a continuation-in-part ofSer. No. 429,164, filed Dec. 28, 1973 (now abandoned)

This invention is directed to a flame retardant polycarbonatecomposition and in particular an aromatic polycarbonate containing inadmixture therewith a particular flame retardant additive which may bethe metal salts of unsubstituted or halogenated oxocarbon acids, ormixtures of these.

BACKGROUND OF THE INVENTION

With the increasing concern for safety, there is a positive move towardsproviding safe materials for public and household use. One particulararea of need is that of providing flame resistant or flame retardantproducts for use by the ultimate consumer. As a result of this demand,many products are being required to meet certain flame retardantcriteria both by local and federal government and the manufacturers ofsuch products. One particular set of conditions employed as a measuringstandard for flame retardancy is set forth in Underwriters Laboratories,Inc. Bulletin 94. This Bulletin sets forth certain conditions by whichmaterials are rated for self-extinguishing characteristics.

In the art, there are many known flame retardant additives which areemployed by mixing with products to render such materialsself-extinguishing or flame retardant. Such flame retardant additiveshave been known to be employed in amounts of 5 to 20 weight percent inorder to be effective in extinguishing burning of those products whichare combustible. It has also been found that such amounts can have adegrading effect upon the base product to be rendered flame retardant,resulting in the losses of valuable physical properties of the baseproduct. This is particularly so when employing known flame retardantadditives with the base product polycarbonate resins. Many of theseknown additives have a degrading effect upon the polymer.

DESCRIPTION OF THE INVENTION

It has now been surprisingly discovered that an aromatic polycarbonatecan be made flame retardant by incorporating with the aromaticpolycarbonate minor amounts of certain additives, which additives areinert and do not degrade the aromatic polycarbonate. The particularadditive employed herein is unique in that even very minor amountsrender the aromatic polycarbonate flame retardant. The amount of theadditive employed herein can vary, preferably, from 0.01 to about 10weight percent based on the weight of the aromatic polycarbonate.

More specifically, the particular additive of this invention is themetal salt of unsubstituted or halogenated oxocarbon acids or mixturesthereof. The metal salt employed in the practice of this invention iseither the alkali metal or alkaline earth metal salt or mixtures ofthese metal salts. The metals of these groups are sodium, lithium,potassium, rubidium, cesium, beryllium, magnesium, calcium, strontiumand barium.

The oxocarbon acids employed in the practice of this invention can besubstituted or unsubstituted wherein the substituent consists offluorine, chlorine and bromine.

Oxocarbon acids are a class of organic compounds which are vinylogs ofcarboxylic acids, that is the OH and CO radicals are joined, notdirectly, but through a vinylic unsaturation forming a cyclicnon-aromatic ring: ##STR1##

As the name further implies, the carbon atoms not involved in the acidicmoiety are substituted by oxygen and are present as carbonyl or hydroxyfunctions. The best known examples of oxocarbon acids are the following:##STR2##

These oxocarbon acids may be substituted with, for example, aromaticrings. Examples of these substituted oxocarbon acids are the following:##STR3##

3-chloro-1,4-napthoquinone-2-ol ##STR4##

2-chloro-4,5,6,7-tetrafluoroindenone-3-ol

Halooxocarbon acids contain the basic acidic feature of the oxocarbonacids, that is, the -CO-C=C-OH moiety, but in some or in all of theother OH and CO functions the oxygen is replaced by halogen. Examples ofthe halooxocarbon acids are the following: ##STR5## While chloranilicacid is widely known, compounds A and B, and related structures, andfluoranilic acid are also well documented in the literature, as are thebenzo-derivatives (with fused benzene rings attached).

The metal salts of the oxocarbon and halooxocarbon acids have thefollowing formula: ##STR6## wherein M is a metal which may be selectedfrom the periodic table of either an alkali or an alkaline earth metal,Y is a halogen radical selected from chlorine, fluorine and bromine, oran --OM radical where M is the same as cited above, and X is a divalentradical selected from the following groups: ##STR7## wherein m and n areintegers from 1-2 and Hal is a halogen selected from chlorine, fluorineand bromine radicals and arylene comprises the phenylene, naphthyleneand anthracenylene radicals.

While there are many compounds that meet the requirements of Formula Iand which offer excellent flame retardant characteristics to an aromaticpolycarbonate, the preferred additives employed in the practice of thisinvention are disodium chloranilate: ##STR8## and sodiumpentachlorobicyclo[3.2.0]-2,6-heptadien-2ol-4-one ##STR9##

The compositions of the instant invention may be used in combinationwith conventional additives such as fillers, pigments, dyes,antioxidants, stabilizers, ultraviolet absorbers, mold release agentsand the like.

PREFERRED EMBODIMENT OF THE INVENTION

In order to more fully and clearly illustrate the present invention, thefollowing specific examples are presented. It is intended that theexamples be considered as illustrative rather than limiting theinvention disclosed and claimed herein. In the examples, all parts andpercentages are on a weight basis unless otherwise specified.

EXAMPLE I

Ninety-nine parts of an aromatic polycarbonate, prepared by reacting2,2-bis(4-hydroxyphenyl)propane and phosgene in the presence of an acidacceptor and a molecular weight regulator and having an intrinsicviscosity of 0.57 is mixed with 1 part of a finely ground dehydratedadditive listed in Table I by tumbling the ingredients together in alaboratory tumbler. The resulting mixture is then fed to an extruder,which extruder is operated at about 265° C., and the extruder iscomminuted into pellets.

The pellets are then injection molded at about 315° C. into test bars ofabout 5 in. by 1/2 in. by about 1/16-1/2 in. thick. The test bars (5 foreach additive listed in the Table) are subject to the test procedure setforth in Underwriters Laboratories, Inc. Bulletin UL-94, Burning Testfor Classifying Materials. In accordance with this test procedure,materials so investigated are rated either SE-O, SE-I or SE-II based onthe results of 5 specimens. The criteria for each SE rating per UL-94 isbriefly as follows:

"SE-O": --Average flaming and/or glowing after removal of the ignitingflame shall not exceed 5 seconds and none of the specimens shall dripflaming particles which ignite absorbent cotton.

"SE-I":--Average flaming and/or glowing after removal of the ignitingflame shall not exceed 25 seconds and the glowing does not travelvertically for more than 1/8inches of the specimen after flaming ceasesand glowing is capable of igniting absorbent cotton.

"SE-II": --Average flaming and/or glowing after removal of the ignitingflame shall not exceed 25 seconds and the specimens drip flamingparticles which ignite absorbent cotton.

In addition, a test bar which continues to burn for more than 25 secondsafter removal of the igniting flame is classified, not by UL-94, but bythe standards of the instant invention, as "burns". Further, UL-94requires that all test bars in each test group must meet the SE typerating to achieve the particular classification. Otherwise, the 5 barsreceive the rating of the worst single bar. For example, if one bar isclassified as SE-II and the other four (4) are classified as SE-O, thenthe rating for all 5 bars is SE-II.

The results of the different additives within the scope of the instantinvention are as follows with a control being the aromatic polycarbonateas prepared above without the additive of the type set forth herein.

                  TABLE 1                                                         ______________________________________                                                      Flame Out   No. of                                              Additive      Time        Drips Per                                           (1.0 weight percent)                                                                        Seconds (Avg.)                                                                            Test Bar  Rating                                    ______________________________________                                        CONTROL       31.6        4+        Burns                                     Disodium squarate                                                                           5.3         2.5       SE-II                                     Barium rhodizonate                                                                          5.3         3.2       SE-II                                     Disodium chloranilate                                                                       2.4         0         SE-0                                      Calcium chloranilate                                                                        2.8         2.4       SE-II                                     Disodium croconate                                                                          5.5         2.8       SE-II                                     ______________________________________                                    

EXAMPLE II

This Example is set forth to demonstrate the effect of the flameretardant additives of this invention at the lower limits of 0.01 weightpercent based on the weight of the polymer composition.

In preparing the test bars for this Example, 99.99 parts of thepolycarbonate of Example I is mixed with 0.01 weight percent of theadditives listed in Table 2 employing the same procedure. Test bars arethen molded using the same procedure employed in Example I. The testbars are subjected to the same test procedure of Example I with thefollowing results:

                  TABLE 2                                                         ______________________________________                                                      Flame Out   No. of                                              Additive      Time        Drips Per                                           (1.0 weight percent)                                                                        Seconds (Avg.)                                                                            Test Bar  Rating                                    ______________________________________                                        CONTROL       31.6        4+        Burns                                     Disodium chloranilate                                                                       9.6         4.2       SE-II                                     Barium chloranilate                                                                         10.6        3.2       SE-II                                     ______________________________________                                    

EXAMPLE III

This Example is set forth to show the effect of a known commerciallyavailable flame retardant additive.

A.

Example I is repeated except that in place of the additives employedtherein, only 1 part 1,2,4,5,9,10-hexabromocyclododecane is used herein.The results obtained upon evaluating five (5) test bars are the same asobtained for the Control shown in Table 1 above.

B.

Part A. above is repeated but using 5 weight percent of the aboveadditive, namely 1,2,5,6,9,10-hexabromocyclododecane. The resultsobtained are the same as obtained in Part A. above.

C.

Part A. above is repeated but using 10 weight percent of the aboveadditive, namely 1,2,5,6,9,10-hexabromocyclododecane. At this level ofadditive, test bars are rated SE-II. However, the polycarbonate is badlydegraded as evidenced by severe dark streaking of the molded test bars,which degradation does not occur with the additives of the instantinvention.

Example IV

Example III is repeated except that hexabromobiphenyl is employedherein. The results obtained are essentially the same as those ofExample III.

Example V

Example III is repeated except that the additive employed herein is acombination of antimony oxide and a material which is a mixture ofpolychlorinated biphenyl (Arocior by Monsanto Company). The proportionof the ingredients of the additive employed in this example is based on3 parts of chlorine per 1 part of antimony. The results obtained at 1weight percent and 5 weight percent amounts are the same as in ExampleIII.

However, at the higher amount, namely 10 weight percent, flameretardancy effect is noted, but with, again, severe degradation of thepolycarbonate, as evidenced by the substantial reduction in theintrinsic viscosity of the molded test bars. As molded, the intrinsicviscosity of the test bars with 1 weight percent of the above additiveis about 0.50. The instrinsic viscosity of the molded test barscontaining 10 weight percent of the flame retardant additive of thisExample is 0.253. This shows the severe degradation of the polycarbonatewhen employing this type of well known flame retardant.

In the practice of this invention, aromatic carbonate polymers arerendered flame retardant by the addition of certain particular additiveswhich are the metal salts of halogenated or unsubstituted oxocarbonacids, or mixtures of these. The amount of the additives employed in thepractice of this invention may vary from 0.01 to up to that amount whichdoes not cause degradation in the physical properties of the carbonatepolymer. This is generally up to about 10 weight percent based on theweight of the aromatic carbonate polymer but may be higher. The amountof the additive to be employed can also be a function of the degree offlame retardancy desired.

It is not exactly understood how the additive of this inventionfunctions or how such minor amounts can act as an effective flameretardant for the aromatic carbonate polymer. Analysis of thecomposition of this invention after being subjected to a firetemperature of about 600° C. showed an unusually high percentage ofremaining char. This leads one to hypothesize that the additive may actas a cross-linking agent when the aromatic carbonate polymer issubjected to fire temperatures. However, it is emphasized that this isonly theory and should not be construed as actually occuring.

As indicated previously, the additive of the instant invention comprisesthe alkali or alkaline earth metal salts of the halogenated andunsubstituted oxocarbon acids or mixtures of these. While a great numberof such salts are set forth in the tables of the Examples of the instantinvention, these are only a representative sample of the additives ofthis invention. The sodium, calcium, magnesium, potassium, strontium,lithium, barium, rubidium and cesium salts of other halogenated orunsubstituted oxocarbon acids can be employed in place of those of theExamples with the same effective flame retardancy being achieved. Theseother metal salts of oxocarbon acids are obtained from the followingspecies:

3-chloro-1,4-naphthoquinone-2-ol

3,5,6,7,8-pentachloro-1,4-naphthoquinone-2-ol

2-chloro-4,5,6,7-tetrafluoroindenon-3-ol

2,4,4-trichlorocyclopenten-3,5-dione-1-ol

bromanilic acid

fluoranilic acid

pentachloro-2-cyclopenten-3-ol-1-one.

In the practice of this invention, the additive is generally prepared bywell known methods in the art, such as the neutralization of theoxocarbon acid with the alkali or alkaline earth metal hydroxide. Thesalt is recovered by precipitation or by removal of the solvent, anddried prior to use.

In the practice of this invention, any of the aromatic polycarbonatescan be employed herein. These are homopolymers and copolymers andmixtures thereof that are prepared by reacting a dihydric phenol with acarbonate precursor. Typical of some of the dihydric phenols that may beemployed in the practice of this invention are bisphenol-A,(2,2-bis(4-hydroxyphenyl) propane), bis(4-hydroxyphenyl) methane,2,2-bis(4-hydroxy-3-methylphenyl) propane,4,4-bis(4-hydroxyphenyl)heptane, 2,2-(3,5,3',5'-tetrachloro-4,4'-dihydroxydiphenyl)propane,2,2-(3,5,3',5'-tetrabromo-4,4'-dihydroxydiphenyl)propane,(3,3'-dichloro-4,4'-dihydroxyphenyl)methane. Other dihydric phenols ofthe bisphenol type are also available and are disclosed in U.S. Pat.Nos. 2,999,835, 3,028,365 and 3,334,154.

It is, of course, possible to employ two or more different dihydricphenols or a copolymer of a dihydric phenol with a glycol or withhydroxy or acid terminated polyester, or with a dibasic acid in theevent a carbonate copolymer or interpolymer rather than a homopolymer isdesired for use in preparation of the aromatic carbonate polymers ofthis invention. Also employed in the practice of this invention may beblends of any of the above materials to provide the aromatic carbonatepolymer.

The carbonate precursor may be either a carbonyl halide, a carbonateester of a haloformate. The carbonyl halides which can be employedherein are carbonyl bromide, carbonyl chloride and mixtures thereof.Typical of the carbonate esters which may be employed herein arediphenyl carbonate, di-(halophenyl) carbonates such as di-(chlorophenyl)carbonate, di-(bromophenyl) carbonate, di-(trichlorophenyl) carbonate,di-(tribromophenyl) carbonate, etc., di-(alkylphenyl) carbonate such asdi(tolyl) carbonate, etc., di-(nephthyl) carbonate,di-(chloronaphthyl)carbonate, phenyl tolyl carbonate, chlorophenylchloronaphthyl carbonate, etc., or mixtures thereof. The haloformatessuitable for use herein include bis-haloformates of dihydric phenols(bischloroformates of hydroquinone, etc.) or glycols (bishaloformates ofethylene glycol, neopentyl glycol, polyethylene glycol, etc.). Whileother carbonate precursors will occur to those skilled in the art,carbonyl chloride also known as phosgene is preferred.

Also included are the polymeric derivatives of a dihydric phenol, adicarboxylic acid and carbonic acid. These are disclosed in U.S. Pat.No. 3,169,121 which is incorporated herein by reference.

The aromatic carbonate polymers of this invention may be prepared byemploying a molecular weight regulator, an acid acceptor and a catalyst.The molecular weight regulators which can be employed in carrying outthe process of this invention include monohydric phenols such as phenol,chroman-I, paratertiary-butylphenol, parabromophenyl, primary andsecondary amines, etc. Preferably, phenol is employed as the molecularweight regulator.

A suitable acid acceptor may be either an organic or an inorganic acidacceptor. A suitable organic acid acceptor is a tertiary amine andincludes such materials as pyridine, triethylamine, dimethylaniline,tributylamine, etc. The inorganic acid acceptor may be one which can beone which can be either a hydroxide, a carbonate, a bicarbonate, or aphosphate of an alkali or alkaline earth metal.

The catalysts which are employed herein can be any of the suitablecatalysts that aid the polymerization of bisphenol-A with phosgene.Suitable catalysts include tertiary amines such as for example,triethylamine, tripropylamine, N,N-dimethylaniline, quaternary ammoniumcompounds such as for example tetraethylammonium bromide, cetyl triethylammonium bromide, tetra-n-heptylammonium iodide, tetra-n-propyl ammoniumbromide, tetramethylammonium chloride, tetramethyl ammonium hydroxide,tetra-n-butylammonium iodide, benzyltrimethylammonium chloride andquaternary phosphonium compounds such as for example, n-butyltriphenylphosphonium bromide and methyltriphenyl phosphonium bromide.

Also, included herein are branched polycarbonates wherein apolyfunctional aromatic compound is reacted with the dihydric phenol andcarbonate precursor to provide a thermoplastic randomly branchedpolycarbonate.

These polyfunctional aromatic compounds contain at least threefunctional groups which are carboxyl, carboxylic anhydride, haloformylor mixtures thereof. Examples of these polyfunctional aromatic compoundswhich may be employed in the practice of this invention include:trimellitic anhydride, trimellitic acid, trimellityl trichloride,4-chloroformyl phthalic anhydride, pyromellitic acid, pyromelliticdianhydride, mellitic acid, mellitic anhydride, trimesic acid,benzophenonetetracarboxylic acid, benzophenonetetracarboxylic anhydrideand the like. The preferred polyfunctional aromatic compounds aretrimellitic anhydride or trimellitic acid, or their haloformylderivatives.

Also, included herein are blends of a linear polycarbonate and abranched polycarbonate.

It will thus be seen that the objects set forth above among those madeapparent from the preceding description are efficiently attained andsince certain changes may be made in carrying out the above process andin the composition set forth without departing from the scope of thisinvention, it is intended that all matters contained in the abovedescription shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. A flame retardant aromatic carbonate polymercomposition comprising in admixture an aromatic carbonate polymer and aminor amount of an additive selected from the group consisting of themetal salt of unsubstituted and halogenated oxocarbon acids, andmixtures thereof, wherein said metal salts thereof are selected from thegroup consisting of alkali metals and alkaline earth metals, andmixtures thereof, and said halogen is selected from fluorine, chlorineand bromine, and said oxocarbon acids are characterized by having themoiety ##STR10## forming a cyclic non-aromatic ring in their structure.2. The composition of claim 1 wherein the metal salt of theunsubstituted and halogenated oxocarbon acids have the followingformulae: ##STR11## wherein M is selected from the group consisting ofalkali metals and alkaline earth metals, Y is an --OM radical wherein Mhas the meaning recited above or a halogen radical independentlyselected from the group consisting of chlorine, fluorine, bromine, and Xis a divalent radical selected from the group consisting of ##STR12##wherein m and n are integers from 1-2, Hal is a halogen independentlyselected from the group consisting of chlorine, fluorine and bromine,and arylene is an aromatic radical of from 1-3 aromatic rings and isselected from the group consisting of phenylene, naphthylene andanthracenylene radicals.
 3. The composition of claim 2 wherein Hal ischlorine.
 4. The composition of claim 2 wherein the additive is disodiumsquarate.
 5. The composition of claim 2 wherein the additive is disodiumcroconate.
 6. The composition of claim 1 wherein the additive is bariumrhodizonate.
 7. The composition of claim 1 wherein the additive iscalcium chloranilate.
 8. The composition of claim 1 wherein the additiveis said metal salt of 3-chloro-1,4-naphthoquinone-2-ol.
 9. Thecomposition of claim 1 wherein the additive is said metal salt of2-chloro-4,5,6,7-tetrafluoroindenon-3-ol.
 10. The composition of claim 1wherein the additive is said metal salt of fluoranilic acid.
 11. Thecomposition of claim 1 wherein the additive is said metal salt of3,5,6,7,8-pentachloro-1,4-naphthoquinone-2-ol.
 12. The composition ofclaim 1 wherein the additive is said metal salt of2,4,4-trichlorocyclopenten-3,5-dione-1-ol.
 13. The composition of claim1 wherein the additive is said metal salt of bromanilic acid.